inv_logit.hpp

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#ifndef __STAN__AGRAD__REV__INV_LOGIT_HPP__
#define __STAN__AGRAD__REV__INV_LOGIT_HPP__

#include <stan/agrad/rev/var.hpp>
#include <stan/math/functions/inv_logit.hpp>
#include <stan/agrad/rev/op/v_vari.hpp>

namespace stan {
  namespace agrad {

    namespace {
      class inv_logit_vari : public op_v_vari {
      public:
        inv_logit_vari(vari* avi) :
        op_v_vari(stan::math::inv_logit(avi->val_),avi) {
        }
        void chain() {
          avi_->adj_ +=  adj_ * val_ * (1.0 - val_);
        }
      };
    }

    inline var inv_logit(const stan::agrad::var& a) {
      return var(new inv_logit_vari(a.vi_));
    }

  }
}
#endif